Liquid ebonite mixtures (LEM) are well known in the art. A liquid ebonite mixture, noted for its excellent abrasion and chemical resistance, is ideally suited for coatings such as monolithic thick-layer coatings. LEM may be used to coat small and intricately shaped articles such as (1) centrifuge rotors for filtration processes and the wheels of pumps and fans, (2) inner surfaces of pipelines, fittings, etc., having small diameters, i.e., less than 32 mm, (3) perforated elements such as screens and mesh, (4) very intricate surface parts, e.g., membranes, (5) parts of chemical apparatuses, reactor vessels, and complex air ducts up to 500 mm in diameter, such as those with joining lips, and (6) galvanic or electrolysis baths and their components. Coating with LEM eliminates the need for an additional glue layer and provides adhesion strength to steel up to 11 MPa in tear-apart tests.
U.S. Pat. No. 4,195,009 issued to Zimmermann in 1980 discloses coating systems based on the use of liquid rubber. However, liquid rubber must be present in the form of hydroxy-terminated rubber, e.g., hydroxy-terminated polybutadiene, which then reacts with a polyether triol and an isocyanate component in the presence of a mercury catalyst, carbon black, low oil-absorbency silica, suspending agent for the latter, lecithin, and molecular sieve desiccant.
U.S. Pat. No. 4,929,469 issued to Kimura, et al., in 1990 discloses a UV-curable surface-protective coating comprising a liquid diene rubber of molecular weight from 1,000 to 10,000 and having one or more hydroxyl groups. Additionally, a diisocyanate component, a diol, and an ethylenically unsaturated monomer having at least one hydroxy group must be present, and the composition is then screen printed and cured by UV radiation to form a coating that is easily peeled from a printed circuit board after plating and soldering. Therefore, the coating systems disclosed in these references are based on polyurethane chemistry and not on rubber vulcanization.
A liquid ebonite mixture composition is disclosed in U.S. Pat. No. 6,303,683 issued to Figovsky in 2001. The composition contains high-molecular-weight rubber (in an amount of up to 4 parts by weight of the number-average molecular weight low-molecular-weight rubber) used for increasing viscosity of the liquid ebonite mixture and thus for preventing problems of sagging. Unfortunately, the high viscosity of such compositions makes handling and inspection of the coating before vulcanization impractical.
Rappoport has disclosed a liquid rubber-based ebonite coating in U.S. Pat. No. 5,766,687 issued in 1998 and U.S. Pat. No. 5,997,953 issued in 1999. Compositions disclosed in these prior art patents contain epoxidized liquid rubber, amines, sulfur, accelerators, and fillers. However, backbone epoxy groups and amines react with difficulty, and therefore the structure of the polymer network is subject to breakage.
Two component mixtures of unsaturated liquid polymers, sulfur, accelerators, and fillers are disclosed by Chang, et al, in U.S. Pat. No. 6,482,894 and by Betts, III, et al, in U.S. Pat. No. 6,486,259, both issued in 2002. One such mixture of unsaturated liquid polymers includes terminal isocyanate groups, thereby increasing handling difficulty and environmental pollution.
The blending of an epoxy coating with an ebonite coating in a mix ratio of 95/5 to 5/95 has been disclosed by Chang, et al, in U.S. Pat. No. 7,005,483 issued in 2006. The epoxy part of the composition includes an epoxy resin of a non-rubber nature and an epoxy curing agent. The ebonite part of the composition includes liquid rubber, wherein said liquid rubber comprises two terminal reactive functional groups, a sulfur vulcanization agent, a vulcanization accelerator, and a vulcanization activator. Such composition is a multicomponent mixture and is inconvenient to handle.
The article by Y. N. Pushkarev and O. L. Figovsky, entitled “Protective ebonite coatings on the base of oligobutadienes” published in Journal Anti-Corrosion Methods and Materials, V. 46, No. 4, 1999, pp. 261-267, describes the results obtained from experimental studies on vulcanization processes conducted by Polymate Ltd. (Israel). It has been found that the most effective bonding material for non-solution compositions is an ebonite coating which can be applied onto prepared surfaces by conventional methods used in lacquer-paint coating technology.
The article by O. L. Figovsky and N. B. Blank, entitled “Liquid Ebonite Mixtures for Anticorrosive Coverings”, published in International Conference on Corrosion In Natural and Industrial Environments: Problems and Solutions, sponsored by NACE International Italia Section, Grado, Italy, 1995, pp. 593-596, described new protective coatings made from ebonite mixtures based on linear low-molecular polybutadiene rubber. These coatings demonstrated chemical resistance to aggressive media.
The article by O. L. Figovsky et. al., entitled “Rubber matrix as the base for preparation of new class of effective corrosion-resistant composites for building—Cautons”, published in Scientific Israel—Technological Advantage, V. 1. No. 2. pp. 53-58, describes rubber as a matrix for a polymer concrete with high chemical resistance. The authors have found the most optimal matrix named rubber concrete based on four different type of liquid low-molecular-weight polybutadienes.
However, the aforementioned various known compositions possess a number of disadvantages. For example, they require the use of a multi-component liquid ebonite that needs premixing and cannot provide coating of sufficiently high physical and mechanical properties. Further more, the assortment of organic and inorganic and inorganic fillers and aggregates with which the known liquid compositions can be combined is limited. Some of the known compositions form binders that contain volatile styrene monomers the use of which is undesirable. Furthermore, although the protective coatings prepared from the above-described liquid compositions possess chemical resistance to aggressive media, this property is still insufficient with regard to some acids and alkalis. In addition, better adhesion is required for binding to steel reinforcement components typically used in reinforced structural concrete.